A free electron laser oscillator which utilizes laser injection to stimulate the growth of an output beam.
Infrared free electron laser oscillators in the Compton, or low density, high voltage regime are regenerative devices which require a very long time (about 100 microseconds) to achieve a high power output due to the requirement that the signal grow out of electron beam noise. This has been successfully demonstrated at a wavelength of 3 .mu.m using a very long electron beam pulse (1000 microseconds) from a superconducting linac electron source. Additionally, storage ring free electron lasers can, in principle, provide the very long time-duration electron beam current required for an infrared free electron laser oscillator output to grow out of noise, although this has not yet been demonstrated.
Conventional short-pulse (approximately 1 .mu.sec) electron sources, such as the RF-linac, have definite advantages over both the superconducting linac and the storage ring laser system in cost, convenience, and compactness. However, these short pulse sources generally have too short a macropulse output for the oscillator output to grow out of the beam noise.
The present Invention provides a novel free electron laser oscillator which is capable of producing an output beam when supplied with an input electron beam from a conventional short-pulse electron source.